|Publication number||US5893722 A|
|Application number||US 08/843,116|
|Publication date||Apr 13, 1999|
|Filing date||Apr 28, 1997|
|Priority date||Jun 28, 1996|
|Also published as||CA2257888A1, CA2257888C, DE69711878D1, DE69711878T2, DE69726322D1, DE69726322T2, EP0907994A1, EP0907994B1, EP1176680A1, EP1176680B1, US5764674, WO1998000895A1|
|Publication number||08843116, 843116, US 5893722 A, US 5893722A, US-A-5893722, US5893722 A, US5893722A|
|Inventors||Mary K. Hibbs-Brenner, James R. Biard|
|Original Assignee||Honeywell Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (81), Classifications (23), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a division, of application Ser. No. 08/671,995 filed Jun. 28, 1996.
The present invention pertains to vertical cavity surface emitting lasers (VCSELs), and particularly to VCSELs having current confinement. More particularly, the invention pertains to VCSELs having refined current confinement caused by an implant or diffusion not having unwanted damage in the VCSEL structure.
Several patents address the issue of current confinement. U.S. Pat. No. 5,115,442 reveals a structure having a semiconductor quarterwave stack in both mirrors. The entire semiconductor epitaxial structure is deposited first, followed by a deep proton implant to confine the current. This is a commonly used structure. Its drawbacks include the fact that the top mirror is several microns thick, and therefore the implant must be so deep that one is limited in how small the current path can be made. Since the depth is so large, and there is significant straggle of implanted ions, the diameter of the current confined region cannot be made as small as one would like. This makes it more difficult to produce a single mode device and more difficult to keep the current required to reach the threshold for lasing small. In addition, damage is produced in proximity to the active region by the implant, which could eventually limit the lifetime of the device. The limit on size restricts performance. Furthermore, there are reliability concerns due to the proximity of the implanted region next to the gain region.
A second related U.S. Pat. No. 5,256,596 also provides for current confinement using ion implantation, but has a mesa etched before the implanting, so the implant depth is smaller. In that structure, a buried implant is used to provide current confinement. However, the entire epitaxial structure is deposited first, and a mesa must be etched before ion implant, in order to place the implant at the right depth, since the range of dopant atoms is quite small compared to protons. In fact, one can wonder whether the structure shown in FIG. 3 of that patent is even feasible, since it would require the implant of p- type atoms several microns below the surface. The disadvantages of this approach are that it results in a non-planar surface, and requires implantation through or close to the active region, thereby resulting in potential reliability problems.
U.S. Pat. 5,475,701, by Mary Hibbs-Brenner and issued Dec. 12, 1995, is hereby incorporated in this specification by reference.
This invention consists of a vertical cavity surface emitting laser in which the current is confined to the center of the device by the use of an implant or diffusion in mirror layers close to the active layers of either mirror; that is, the implant or diffusion may be placed at the top of the bottom mirror or at the bottom of the top mirror.
The approach outlined here involves a two step metalorganic chemical vapor deposition (MOCVD) growth. The first mirror is grown, and then implanted or diffused to provide current confinement. Then the remainder of the laser structure, i.e., the remainder of the first mirror, the gain region, and the second mirror, is deposited. The structure remains planar, thus facilitating the fabrication of high density arrays. The implant or diffusion is shallow (a few tenths of a micron), so the dimensions can be accurately controlled. The implant or diffusion is clearly below the active region, and ions do not need to be implanted or diffused through the active region. This approach provides a structure for improved reliability.
FIG. 1a is a diagram of a VCSEL having a current confining implant or diffusion below the active region.
FIG. 1b shows a current confining implant or diffusion above the active region in the VCSEL.
FIG. 2a is a diagram of another VCSEL, having a current confining implant or diffusion below the active region, that can be integrated with other electronic circuits.
FIG. 2b shows the VCSEL of FIG. 2a but with the current confining implant or diffusion above the active region.
FIG. 1a illustrates configuration 10 of the structure. In this version, alternating epitaxial layers 14 and 16 for laser 10 are deposited on a substrate 12 which is doped n- type. On the bottom side of substrate 12 is formed a broad area contact 15 (i.e., n- ohmic). A bottom mirror 17, consisting of 26 periods of alternating layers of AlAs 16 and Alx Ga.sub.(1-x) As (x=0.15 is preferred, but x may have any value greater than 0.05) 14, all doped n- type, are grown to form a highly reflecting mirror 17. The total number of mirror periods may be greater or less than 26, depending on other parameters. At the top of mirror 17, a p- type or electrically insulating dopant 20 is implanted or diffused in top layers 16 and 14 in order to block current flow on the perimeter of mirror 17, and confine the current to dimension 40. This p- or insulating dopant may be located between 0 and 10 periods (20 layers) below the first confining layers, but preferably is 2 periods below the first confining layer. It is preferable for the depth of implant 20 to be several tenths of a micron but may range between 0.1 and 2 microns. Dimension 40 may be between 0.1 and 60 microns, but is typically several microns, i.e., 2 to 5 microns. Several more mirror periods (0 to 10) may be formed on top of the implanted or diffused surface followed by the mid-portion of structure 10, which consists of two Alx Ga.sub.(1-x) As (x=0.6) confining layers 24. x may be 0.25 or greater. These layers 24 are most likely to be lightly doped, n-type on the layer nearest the n-doped mirror, and p-type on the layer nearest the p-type mirror, although there is a possibility that these could be left undoped. Layers 24 sandwich a region 22 having three GaAs quantum wells 28, separated from one another and confining layers 24 by four Alx Ga.sub.(1-x) As (x=0.25) barrier layers 26. The number of GaAs quantum wells may be from one to five. Alternatively, one could potentially have an active region 22 without quantum wells, e.g., a region having an emitting number of about 0.2 micron thick. On top of confining layer 24 on active region 22, a p- type mirror 30 is grown, consisting of 18 periods of alternating layers of p- AlAs 31 and p- Alx Ga.sub.(1-x) As 32 (x=0.15 preferably, but may have any value greater than 0.05). The number of periods may be greater or less than 18, depending on other parameters. A GaAs contact layer 34 is formed on top of mirror 30. A proton isolation implant 38 is placed at the perimeter of contact layer 34, mirror 30, active region 22 and confining layers 24, to separate one device 10 from a like neighboring device on a chip. If a single laser chip 10 were to be made, then it is possible that one could eliminate this proton implant 38, if the implant or diffusion made on top of the n-mirror were to extend all the way to the edge of the chip. Laser 10 connections are formed by depositing at least one p- type ohmic contact 36 on the top surface of contact layer 34, and a broad area n- type ohmic contact 15 on the back side of wafer substrate 12. The resulting device 10 emits laser light in the range of 760 to 870 nanometers (nm).
FIG. 1b shows the same VCSEL structure as FIG. 1a, except that dopant 20 is implanted or diffused as an n- type or electrically insulating dopant in layers 31 and 32 of mirror 30, preferably several layers above confining layer 24, to function in blocking current flow from the perimeter of active region 22 and lower mirror 17, and to confine the current flow within dimension 40. Dopant 20 has similar dimensions as implant or diffusion 20 of FIG. 1a.
FIG. 2a illustrates configuration 50 of the structure wherein both contacts of the p-n junction can be made from a top surface thereby permitting integration with electronic circuits or other devices on a semi-insulating substrate. In this version, epitaxial layers 14 and 16 for laser 50 are deposited on a semi-insulating substrate 12. A bottom mirror 17 has 26 periods (i.e., 52 layers) of alternating layers of AlAs 16 and Alx Ga.sub.(1-x) As (x=0.16) 14, of which all can be doped n- type, be entirely undoped, or be undoped except for the last few periods. Layers 16 and 14 are grown to form a highly reflecting mirror 17. A contact layer 54 of n- doped Alx Ga.sub.(1-x) As (x=0.10 but could range from 0.0 to 0.20) is formed on the top layer 16 of mirror 17. In contact layer 54, a p- type or electrically insulating dopant 20 is implanted or diffused in order to block current flow on the perimeter of mirror 17 and confine current flow to dimension 40. Dopant 20 has similar dimensions as implant 20 of FIG. 1a. Unlike the description for FIG. 1a, in this case, the p-type or electrically insulating dopant region cannot extend all the way to the edge of the chip, because it would then prevent us from making this n-ohmic contact 52. The p-type or electrically insulating implant or diffused area 20 looks like a ring. Dimension 40 is typically between two and five microns. The top and mid-portions of structure 50 form a mesa on contact layer 54, after etching. The mid-portion consists of two undoped Alx Ga.sub.(1-x) As (x=0.6 but may have a value of 0.25 or greater) confining layers 24 which sandwich a region 22 having three undoped GaAs quantum wells 28, separated from one another and confining layers 24 by Alx Ga.sub.(1-x) As (x=0.25 as preferred value) barrier layers 26. On top of confining layer 24 on active region 22, a p- type mirror 30 is grown, consisting of 18 periods of alternating layers of p- AlAs 31 and p- Alx Ga.sub.(1-x) As 32 (x=0.15 but x may be at a value of 0.05 or greater). A p+ GaAs contact layer 34 is formed on top of mirror 30. Layers 34, 31, 32, 26, 28 and 24 are etched on their perimeters down to the contact layer to form a mesa on layer 54. Proton isolation implant 38 may be inserted at the perimeter of contact layer 34, mirror 30, active region 22, and confining layers 24 of the mesa to isolate current from the edge of the mesa. Device 50 could still be fabricated without this proton implant, though it may be more reliable with it. The proton isolation implant may extend into a portion of contact layer 54 at a depth which is less than the thickness of layer 54. The distance between the inside edges of proton implant is between 10 and 100 microns. Laser 50 connections for the p-n junction are formed by depositing at least one p- type ohmic contact 36 on the top surface of contact layer 34, and at least one n- type ohmic contact 52 on an external surface of contact layer 54 outside the perimeter of the mesa incorporating active region 22 and mirror 30, and also outside the perimeter of the p-type or electrically insulating implant or diffusion.
FIG. 2b shows the same VCSEL structure with similar dimensions and materials as FIG. 1a, except that the dopant 20 is implanted or diffused as an n- type or electrically insulating dopant in layers 31 and 32 of mirror 30, preferably several layers (0 to 10 periods, or 0 to 20 layers) above confining layer 24, to function in blocking current flow from the perimeter of active region 22 and lower mirror 17, and confining the current flow within dimension 40.
Device 10, 50 can be fabricated by epitaxially depositing an n- type mirror in an OMVPE (Organo-Metallic Vapor Phase Epitaxy) or MBE (Molecular Beam Epitaxy) reactor. The layers of device 10, 50 are removed from the reactor forming the layers, and photoresist is spun onto wafer 10, 50 and patterned in such a way as to protect the layers at an area for a center 40 of device 10, 50. The p-, n-, or electrically insulating type dopant is implanted or diffused in a ring outside the protected area having diameter 40. Device 10, 50 is placed back in the epitaxial growth reactor, and the remaining layers of the structure are deposited. After growth of the material, the proton isolation implant 38, and n- and p- ohmic contact 15 and 36 depositions, respectively, are made using normal semiconductor processing techniques. When device 10, 50 is operated by applying a forward bias to the p-i-n junction formed by the top p- doped mirror 30, undoped, or lightly doped active region 22, and bottom n- doped mirror 17, the current is forced to flow only through unimplanted center 40 of device 10, 50.
In the present invention, which has advantages over the above-noted U.S. Pat. No. 5,115,442, the depth of the p- n-, or electrically insulating type implant or diffusion need only be a few tenths of a micron but may range from 0.1 to 2 microns. Therefore, the diameter 40 of the unimplanted or non-diffused region can be kept small to several microns, but may range from 0.1 to 60 microns, with the realization of needing only a very low current to reach lasing threshold, in the cases when this dimension is kept to just a few microns. In addition, the damage due to implant 20 is kept away from the active region 22 of laser 10 and 50, and thus increases device reliability.
This invention provides advantages over the structure disclosed in the above-noted U.S. Pat. No. 5,256,596. Since the epitaxial growth is carried out in two steps, with confining implant or diffusion 20 performed after the first growth, one need only implant or diffuse a few tenths of a micron. In the case of an implant, this limits the energies required, again allowing tighter control of dimensions, and eliminating the need for a mesa etch before the implant. That mesa etch exposes the very reactive AlAs layers 31 in top mirror 30, which would affect reliability. The lower implant 20 energies limit implant damage and magnitude of the implant straggle. In addition, by keeping implant 20 several periods above or below the active region 22, it keeps the reliability limiting implant away from the active layers of the laser.
Other configurations of the device would include the growth of a p- type mirror 17 first, with an n- type or electrically insulating implant or diffusion 20, followed by the active region 22 and an n- type mirror 30. In addition, InGaAs quantum wells 28 can be used for emission in the range of 870-1000 nm. In that case, light can be emitted from either the top or bottom surface of laser 10 or 50. Other materials can be used, such as the AlGaInP material system which results in a laser 10 or 50 emitting in the range 630-700 nm, or the InGaAsP material system for a device 10 or 50 emitting near 1.3 microns. Even in the case of the lasers emitting at 760-870 nm, the various compositions mentioned in the descriptions above can be varied, i.e., "x" compositions in the mirror might vary from 0.05 to 0.3, or the confining layer "x" compositions might vary from 0.4 to 0.8 at the mirrors and from 0.1 to 0.5 between the quantum wells.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US5115442 *||Apr 13, 1990||May 19, 1992||At&T Bell Laboratories||Top-emitting surface emitting laser structures|
|US5256596 *||Mar 26, 1992||Oct 26, 1993||Motorola, Inc.||Top emitting VCSEL with implant|
|US5316968 *||Feb 11, 1993||May 31, 1994||At&T Bell Laboratories||Method of making semiconductor surface emitting laser|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5998232 *||Jan 14, 1999||Dec 7, 1999||Implant Sciences Corporation||Planar technology for producing light-emitting devices|
|US6064683 *||Dec 12, 1997||May 16, 2000||Honeywell Inc.||Bandgap isolated light emitter|
|US6256333 *||Dec 12, 1997||Jul 3, 2001||Honeywell Inc.||VCSEL structure insensitive to mobile hydrogen|
|US6382228||Aug 2, 2000||May 7, 2002||Honeywell International Inc.||Fluid driving system for flow cytometry|
|US6459719||Nov 3, 2000||Oct 1, 2002||Honeywell Inc||VCSEL structure insensitive to mobile hydrogen|
|US6515305||Sep 17, 2001||Feb 4, 2003||Regents Of The University Of Minnesota||Vertical cavity surface emitting laser with single mode confinement|
|US6522680||Nov 3, 2000||Feb 18, 2003||Honeywell Inc.||VCSEL structure insensitive to mobile hydrogen|
|US6542527||Aug 23, 1999||Apr 1, 2003||Regents Of The University Of Minnesota||Vertical cavity surface emitting laser|
|US6549275||Aug 2, 2000||Apr 15, 2003||Honeywell International Inc.||Optical detection system for flow cytometry|
|US6597438||Aug 2, 2000||Jul 22, 2003||Honeywell International Inc.||Portable flow cytometry|
|US6693933 *||Mar 15, 2001||Feb 17, 2004||Honeywell International Inc.||Vertical cavity master oscillator power amplifier|
|US6700130||Jun 29, 2001||Mar 2, 2004||Honeywell International Inc.||Optical detection system for flow cytometry|
|US6717974 *||Apr 1, 2002||Apr 6, 2004||Lumei Optoelectronics Corporation||Apparatus and method for improving electrical conduction structure of a vertical cavity surface emitting laser|
|US6724798||Dec 31, 2001||Apr 20, 2004||Honeywell International Inc.||Optoelectronic devices and method of production|
|US6738409 *||Dec 28, 2001||May 18, 2004||Honeywell International Inc.||Current confinement, capacitance reduction and isolation of VCSELs using deep elemental traps|
|US6844537||Dec 31, 2001||Jan 18, 2005||Honeywell International Inc.||Method and device for measuring the velocity of a moving surface|
|US6872983||Nov 11, 2002||Mar 29, 2005||Finisar Corporation||High speed optical transceiver package using heterogeneous integration|
|US6964496||Jul 31, 2003||Nov 15, 2005||Benq Corporation||Lamp module and back light device having the same|
|US6970245||Aug 21, 2002||Nov 29, 2005||Honeywell International Inc.||Optical alignment detection system|
|US7000330||Jul 2, 2003||Feb 21, 2006||Honeywell International Inc.||Method and apparatus for receiving a removable media member|
|US7016022||Sep 9, 2004||Mar 21, 2006||Honeywell International Inc.||Dual use detectors for flow cytometry|
|US7023896||Jan 24, 2003||Apr 4, 2006||Finisar Corporation||VCSEL structure insensitive to mobile hydrogen|
|US7026178||Nov 13, 2001||Apr 11, 2006||Applied Optoelectronics, Inc.||Method for fabricating a VCSEL with ion-implanted current-confinement structure|
|US7061595||Dec 20, 2004||Jun 13, 2006||Honeywell International Inc.||Miniaturized flow controller with closed loop regulation|
|US7130046||Sep 27, 2004||Oct 31, 2006||Honeywell International Inc.||Data frame selection for cytometer analysis|
|US7151785||Sep 24, 2003||Dec 19, 2006||Finisar Corporation||Optoelectronic devices and methods of production|
|US7177339 *||Aug 8, 2003||Feb 13, 2007||Osram Opto Semiconductors Gmbh||Semiconductor laser|
|US7215425||Apr 14, 2004||May 8, 2007||Honeywell International Inc.||Optical alignment for flow cytometry|
|US7242474||Jul 27, 2004||Jul 10, 2007||Cox James A||Cytometer having fluid core stream position control|
|US7262838||Jan 16, 2004||Aug 28, 2007||Honeywell International Inc.||Optical detection system for flow cytometry|
|US7277166||May 16, 2005||Oct 2, 2007||Honeywell International Inc.||Cytometer analysis cartridge optical configuration|
|US7283223||Sep 28, 2004||Oct 16, 2007||Honeywell International Inc.||Cytometer having telecentric optics|
|US7306959||Dec 22, 2004||Dec 11, 2007||Finisar Corporation||Methods of fabricating integrated optoelectronic devices|
|US7312870||Oct 31, 2005||Dec 25, 2007||Honeywell International Inc.||Optical alignment detection system|
|US7321117||Sep 22, 2005||Jan 22, 2008||Honeywell International Inc.||Optical particulate sensor in oil quality detection|
|US7471394||Dec 30, 2004||Dec 30, 2008||Honeywell International Inc.||Optical detection system with polarizing beamsplitter|
|US7486387||Apr 4, 2007||Feb 3, 2009||Honeywell International Inc.||Optical detection system for flow cytometry|
|US7553453||Dec 29, 2006||Jun 30, 2009||Honeywell International Inc.||Assay implementation in a microfluidic format|
|US7612871||Sep 1, 2004||Nov 3, 2009||Honeywell International Inc||Frequency-multiplexed detection of multiple wavelength light for flow cytometry|
|US7630063||Sep 9, 2004||Dec 8, 2009||Honeywell International Inc.||Miniaturized cytometer for detecting multiple species in a sample|
|US7630075||Oct 31, 2006||Dec 8, 2009||Honeywell International Inc.||Circular polarization illumination based analyzer system|
|US7641856||May 12, 2005||Jan 5, 2010||Honeywell International Inc.||Portable sample analyzer with removable cartridge|
|US7671987||Jan 6, 2005||Mar 2, 2010||Honeywell International Inc||Optical detection system for flow cytometry|
|US7688427||Apr 28, 2006||Mar 30, 2010||Honeywell International Inc.||Particle parameter determination system|
|US7760351||May 4, 2007||Jul 20, 2010||Honeywell International Inc.||Cytometer having fluid core stream position control|
|US7843563||Aug 16, 2005||Nov 30, 2010||Honeywell International Inc.||Light scattering and imaging optical system|
|US7911617||Oct 2, 2009||Mar 22, 2011||Honeywell International Inc.||Miniaturized cytometer for detecting multiple species in a sample|
|US7978329||Nov 26, 2002||Jul 12, 2011||Honeywell International Inc.||Portable scattering and fluorescence cytometer|
|US8034296||Jun 30, 2006||Oct 11, 2011||Honeywell International Inc.||Microfluidic card for RBC analysis|
|US8071051||May 12, 2005||Dec 6, 2011||Honeywell International Inc.||Portable sample analyzer cartridge|
|US8273294||Jun 30, 2006||Sep 25, 2012||Honeywell International Inc.||Molded cartridge with 3-D hydrodynamic focusing|
|US8323564||Dec 22, 2006||Dec 4, 2012||Honeywell International Inc.||Portable sample analyzer system|
|US8329118||Sep 2, 2004||Dec 11, 2012||Honeywell International Inc.||Method and apparatus for determining one or more operating parameters for a microfluidic circuit|
|US8359484||Sep 23, 2011||Jan 22, 2013||Honeywell International Inc.||Apparatus and method for operating a computing platform without a battery pack|
|US8361410||Jun 30, 2006||Jan 29, 2013||Honeywell International Inc.||Flow metered analyzer|
|US8383043||Dec 22, 2006||Feb 26, 2013||Honeywell International Inc.||Analyzer system|
|US8494018||Jun 17, 2011||Jul 23, 2013||Vixar, Inc.||Direct modulated modified vertical-cavity surface-emitting lasers and method|
|US8540946||Aug 29, 2011||Sep 24, 2013||Honeywell International Inc.||Portable sample analyzer cartridge|
|US8660161||Aug 10, 2012||Feb 25, 2014||Vixar, Inc.||Push-pull modulated coupled vertical-cavity surface-emitting lasers and method|
|US8663583||Dec 27, 2011||Mar 4, 2014||Honeywell International Inc.||Disposable cartridge for fluid analysis|
|US8741233||Dec 27, 2011||Jun 3, 2014||Honeywell International Inc.||Disposable cartridge for fluid analysis|
|US8741234||Dec 27, 2011||Jun 3, 2014||Honeywell International Inc.||Disposable cartridge for fluid analysis|
|US8741235||Dec 27, 2011||Jun 3, 2014||Honeywell International Inc.||Two step sample loading of a fluid analysis cartridge|
|US8828320||Dec 22, 2006||Sep 9, 2014||Honeywell International Inc.||Portable sample analyzer cartridge|
|US8980635||Jan 16, 2014||Mar 17, 2015||Honeywell International Inc.||Disposable cartridge for fluid analysis|
|US8989230||Dec 28, 2012||Mar 24, 2015||Vixar||Method and apparatus including movable-mirror mems-tuned surface-emitting lasers|
|US9088134||Jul 27, 2012||Jul 21, 2015||Vixar Inc.||Method and apparatus including improved vertical-cavity surface-emitting lasers|
|US20040092055 *||Nov 11, 2002||May 13, 2004||Honeywell International Inc.,||High speed otpical transceiver package using heterogeneous integration|
|US20040141536 *||Sep 24, 2003||Jul 22, 2004||Honeywell International Inc.||Optoelectronic devices and methods of production|
|US20040145725 *||Jan 16, 2004||Jul 29, 2004||Fritz Bernard S.||Optical detection system for flow cytometry|
|US20040211077 *||Jul 2, 2003||Oct 28, 2004||Honeywell International Inc.||Method and apparatus for receiving a removable media member|
|US20050105077 *||Sep 9, 2004||May 19, 2005||Aravind Padmanabhan||Miniaturized cytometer for detecting multiple species in a sample|
|US20050106739 *||Dec 20, 2004||May 19, 2005||Cleopatra Cabuz||Miniaturized flow controller with closed loop regulation|
|US20050118723 *||Dec 30, 2004||Jun 2, 2005||Aravind Padmanabhan||Optical detection system with polarizing beamsplitter|
|US20050122522 *||Jan 6, 2005||Jun 9, 2005||Aravind Padmanabhan||Optical detection system for flow cytometry|
|US20050134850 *||Apr 14, 2004||Jun 23, 2005||Tom Rezachek||Optical alignment system for flow cytometry|
|US20050169569 *||Dec 22, 2004||Aug 4, 2005||Yue Liu||Methods for fabricating integrated optoelectronic devices|
|US20050243304 *||May 16, 2005||Nov 3, 2005||Honeywell International Inc.||Cytometer analysis cartridge optical configuration|
|US20050255001 *||May 12, 2005||Nov 17, 2005||Honeywell International Inc.||Portable sample analyzer with removable cartridge|
|US20050255600 *||May 12, 2005||Nov 17, 2005||Honeywell International Inc.||Portable sample analyzer cartridge|
|US20060023207 *||Jul 27, 2004||Feb 2, 2006||Cox James A||Cytometer having fluid core stream position control|
|U.S. Classification||438/45, 438/528, 372/46.015, 438/46, 438/47, 438/526, 372/45.01|
|International Classification||H01S5/042, H01S5/20, H01S5/183, H01S5/343|
|Cooperative Classification||B82Y20/00, H01S5/2059, H01S5/18308, H01S5/1833, H01S5/3432, H01S5/18333, H01S5/18341, H01S5/305, H01S5/3054, H01S5/2063|
|European Classification||H01S5/183C, B82Y20/00|
|Sep 16, 2002||FPAY||Fee payment|
Year of fee payment: 4
|Mar 26, 2004||AS||Assignment|
|Apr 2, 2004||AS||Assignment|
|Oct 13, 2006||FPAY||Fee payment|
Year of fee payment: 8
|Oct 13, 2010||FPAY||Fee payment|
Year of fee payment: 12